1107200
Shadow VI User Manual
page 22
Chapter 2
Installation and Checkout
DANGER
!
STOPPING TIME TOO LONG
Use a brake monitor where a Shadow light curtain is used to protect operators whose hands
are routinely exposed to a hazardous area, as required by OSHA 1910.217 (c) (3) (5).
A brake monitor continually checks that the machine’s stopping time does not exceed a
predetermined limit.
Failure to comply with these instructions will result in death or serious injury.
This is the ANSI B11.1 safety distance formula that Wintriss recommends:
Ds = 63 x (Ts + Tc + Tr + Tbm) + Dpf
D
s
is the ANSI safety distance in inches.
K
is the OSHA-recommended hand-speed constant. This constant is 63 inches-per-second.
The hand-speed constant indicates how far you could theoretically move your hand and arm
in one second.
It is very similar to OSHA's formula, except that it takes more details (such as response
times, brake monitoring setting, and depth penetration factor) into account.
Ts
,
Tc
, and
Tr
are the worst case response times of the press (or other machine)
Ts
,
the control
Tc
, and the
light curtain
Tr
.
Ts
is the stopping time of a press (or other machine) in seconds. It is measured at
approximately 90° of crankshaft rotation (or at maximum closing velocity).
Tc
is the response time of the press control or other machine control. This is the time it takes
for the control to activate the press's brake.
Tr
is the response time of the light curtain. Response time for the Shadow VI is 30 to 40 ms
(30 ms for 6" to 24” models, 35 for 30” to 48” models and 40 ms for the 60” model).
Tbm
is the additional stopping time of the press (or other machine) allowed by the brake
monitor. The brake monitor you use with your press control (or other control) stops the press
when the preset stop time is exceeded. This means excessive brake wear has occurred. It is
time for repair. The brake gradually wears until the limit is reached.
Tbm
allows you to account for brake wear. You add the extra time allowed by the brake
monitor to
Tc
and
Ts
. In other words:
Tbm = brake monitor setting — (Tc + Ts)
Now the gradual increase in stopping time as the brake wear is accounted for up to the limit.
What if you did not account for brake wear? The safety distance would be right at the time
you measured stop time. But as the brake gradually wore, safety distance would be too short
for proper operator protection.
See instructions for your brake monitor to determine the proper brake monitor setting.
Generally, the setting is 120% of the measured stopping time (Tc + Ts) when your brakes are
new. It is 110% of stopping time (Ts + Tc) for older brakes.
Содержание Shadow VI
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